Determination of Flavonoid Content
The flavonoid content of the fruit peel samples were measured using a modified
colorimetric method (Wolfe, 2003). Briefly a volume of 0.25 ml of 0.01g/ml of ethanolic solution of
each fruit peel samples was added to a test tube containing 1.25 ml of distilled water, 0.075 ml
of 5% sodium nitrite solution was added to the mixture, and allowed to stand for 5 min. Then,
0.15 ml of 10% aluminum chloride was added. After 6 min, 0.5 ml of 1 M sodium hydroxide was
added, and the mixture was diluted with another 0.275 ml of distilled water. The absorbance of
the mixture at 510 nm was measured immediately using a spectrophotometer and compared to a
standard curve of prepared catechin solutions. The flavonoid content was expressed as
milligrams of catechin equivalents/g crude extract. The experiments were performed in triplicate.